The John F. Kennedy Center for the Performing Arts opened in Washington, D.C., on 8 September 1971. This institution was originally established by Act of Congress in 1958 as the National Cultural Center, but, following the death of President Kennedy, a law was passed in 1964 renaming it as his sole official memorial in the nation's capital. This paper describes some of the special problems related to noise control that required solution, the basic features of the acoustical design of the halls—a 2759 seat concert hall, a 2319 seat opera house, and a 1142 seat theater—and some of the physical characteristics and acoustical properties of the halls.

The feasibility of performing transmission loss and diffractionmeasurements using correlation techniques is demonstrated. In contrast to standard measurements which make use of reverberant sound fields, the correlation techniques developed herein directly yield the responses due to signals transmitted through and around the acoustic barriers. The technique consists of first cross‐correlating noise signals, then finding the Fourier transform of the resulting impulse response, and finally correcting for source imperfections in the frequency domain. Comparative measurements of the transmission loss of some common materials are presented along with transmission loss measurements made as functions of angle and distance, and also presented are measurements of sound diffraction around panels. The results of these measurements (where comparison is possible) are shown to be as good or better than measurements resulting from standard techniques, and these results are shown to be in excellent agreement with existing theory.

The generation and absorption of surface waves by an interdigital transducer with uniform finger spacing are calculated with the aid of a surface dielectric constant related to the TM‐wave impedance. It is found that the response of an infinite transducer can be calculated with complete consistency, i.e., the field due to the distortion of the piezoelectric medium is correctly included in the determination of the distortion. For a finite transducer, the solutions given are in error only at lines on the surface at either end of the transducer, and are therefore accurate when the transducer is long. It is found that the parallel equivalent circuit derived in the weak coupling approximation is a reasonably accurate representation of the transducer when the coupling is strong and the transducer long, but that the central resonance is then distorted.

Three analytical models for the potential flow through a smooth‐edged orifice are discussed and the prediction of the acoustical inertance obtained from these models is compared with experimentally determined values of orifice inertance as a function of the ratio of wall thickness to orifice diameter. It is shown that the simple hyperbolic wall model predicts corrections for wall thickness which are of the wrong order of magnitude for thin‐walled orifices and are inaccurate for thick‐walled orifices. An improved model, consisting of the super‐position of a hyperbolic flow field and a ring vortex, is used to represent an orifice boundary with finite curvature at the throat and finite thickness. By matching either the curvature or the wall thickness of an orifice, upper and lower bounds for the inertance are obtained. By adding another singularity in the potential flow analysis, both the curvature at the throat and the wall thickness of the actual orifice can be matched, and the values predicted by this model are in good agreement with the experimental results.

A transit detector has been devised that yields a positive response, with high detection probability and a low and reliable false‐alarm rate, whenever a moving sound source completes a transit past the monitoring sensor. The signal rate, instead of the signal amplitude, is processed by sampling periodically the time derivative of the output of a smoothing filter with a very long time constant operating on a rectified broad‐band input signal. Only the algebraic sign of the derivative is retained and this is entered in a shift register. Half the shift register will be filled with ones and the other half with zeros at the end of a transit‐like time variation of the signal component of the input signal‐plus‐noise. This represents a unique binary detection number that can easily be recognized with digital certainty, and the false‐alarm rate can be made arbitrarily small by making the shift register long enough. The selection of optimum design parameters for the processor was studied with a time‐scaled model. The results indicate, for example, that a detection probability of 90%, with a false‐alarm rate of one per 107 samples, can be achieved when the maximum signal‐to‐noise level difference during a transit is no higher than −10.6 dB. Detection sensitivity can be traded off against false‐alarm rate in either direction at an exchange rate of about 0.5 dB for each factor of 10 in false‐alarm rate.

By properly weighting and summing the individual signals received by an array of acoustic sensors, the performance of the array can be improved. In order that the weights can be chosen in a rational manner, some mathematical model must be postulated for the received array data. In this study we examine the effects of a class of data modeling errors on the directivity of linear and nonlinear array processors. We derive a measure of the extent to which the array response may change as a result of Gaussian deviations of the amplitude and phase of the modeled data from those of a nominal model. Among all array processors the simple beamformer is shown to have minimum sensitivity to small model perturbations of this type, and thus to be robust to errors in model selection. For a certain proposed high‐resolution estimator, we show that cases exist in which the sensitivity is very large. An array processor having large sensitivity to modeling errors is mathematically analogous to a superdirective electromagnetic array, with the data model perturbations corresponding to perturbations in the exciting currents, or radiator positions, of the latter. Large perturbation sensitivity of an accoustic array processor is analogous to superdirectivity in phased arrayantenna design.

The acoustic data analysis procedures at various installations differ in the intervals at which readings are converted from volts squared to decibels. There has been much speculation as to what would be the decibel difference between the results obtained for the same data, i.e., the difference between the log of the average and the average of the logs. In this analysis, the difference is treated as a random variable. By making the practical assumption that the distribution of the samples is Gaussian with mean μ and standard deviation σ, the expected value of the difference is found, as well as its appropriate confidence limits, for the special case of small σ/μ. These results are found to depend on the ratio σ/μ and on n, the number of samples averaged. It is found that the expected value of the difference is approximately equal to 2.17[(n − 1)/n] (σ/μ)2 and that the standard deviation of the difference is equal to times this expected value. For practical values of σ/μ the expected value of the difference is found to be less than 0.2 dB and the Chebyshev 95% upper confidence limit of the difference is found to be less than 0.5 dB.

Sound‐velocity measurements were made in fruit and vegetable juices, vegetable oils, sauces, wines, and syrups. The dependence of sound velocity on total solids and on temperature is discussed. Sound velocity values at 25°C are given for 38 products tested. A relationship is described for determining percent solids from sound‐velocity measurements and an expression is given for computing measurement error. Solids measurement accuracies ranging from 0.024% to 0.088% are listed for prune juice, tomato juice, apple juice, applesauce, maple syrup, and corn syrup.